package com.xgkj.diyiketang.security;


import java.io.ByteArrayOutputStream;

public class Base64Util { 
	   private static final char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; 

	   private static byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 }; 

	   private Base64Util() { 
	   } 

	   /** 
	    * 将字节数组编码为字符串 
	    * 
	    * @param data 
	    */ 
	   public static String encode(byte[] data) { 
	       StringBuffer sb = new StringBuffer(); 
	       int len = data.length; 
	       int i = 0; 
	       int b1, b2, b3; 

	       while (i < len) { 
	           b1 = data[i++] & 0xff; 
	           if (i == len) { 
	               sb.append(base64EncodeChars[b1 >>> 2]); 
	               sb.append(base64EncodeChars[(b1 & 0x3) << 4]); 
	               sb.append("=="); 
	               break; 
	           } 
	           b2 = data[i++] & 0xff; 
	           if (i == len) { 
	               sb.append(base64EncodeChars[b1 >>> 2]); 
	               sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); 
	               sb.append(base64EncodeChars[(b2 & 0x0f) << 2]); 
	               sb.append("="); 
	               break; 
	           } 
	           b3 = data[i++] & 0xff; 
	           sb.append(base64EncodeChars[b1 >>> 2]); 
	           sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]); 
	           sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]); 
	           sb.append(base64EncodeChars[b3 & 0x3f]); 
	       } 
	       return sb.toString(); 
	   } 

	   /** 
	    * 将base64字符串解码为字节数组 
	    * 
	    * @param str 
	    */ 
	   public static byte[] decode(String str) { 
	       byte[] data = str.getBytes(); 
	       int len = data.length; 
	       ByteArrayOutputStream buf = new ByteArrayOutputStream(len); 
	       int i = 0; 
	       int b1, b2, b3, b4; 

	       while (i < len) { 

	           /* b1 */ 
	           do { 
	               b1 = base64DecodeChars[data[i++]]; 
	           } while (i < len && b1 == -1); 
	           if (b1 == -1) { 
	               break; 
	           } 

	           /* b2 */ 
	           do { 
	               b2 = base64DecodeChars[data[i++]]; 
	           } while (i < len && b2 == -1); 
	           if (b2 == -1) { 
	               break; 
	           } 
	           buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4))); 

	           /* b3 */ 
	           do { 
	               b3 = data[i++]; 
	               if (b3 == 61) { 
	                   return buf.toByteArray(); 
	               } 
	               b3 = base64DecodeChars[b3]; 
	           } while (i < len && b3 == -1); 
	           if (b3 == -1) { 
	               break; 
	           } 
	           buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2))); 

	           /* b4 */ 
	           do { 
	               b4 = data[i++]; 
	               if (b4 == 61) { 
	                   return buf.toByteArray(); 
	               } 
	               b4 = base64DecodeChars[b4]; 
	           } while (i < len && b4 == -1); 
	           if (b4 == -1) { 
	               break; 
	           } 
	           buf.write((int) (((b3 & 0x03) << 6) | b4)); 
	       } 
	       return buf.toByteArray(); 
	   } 
	}
